CONFIG_ARCH_DAVINCI644x is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_ARCH_DAVINCI644x.
Result is shown for kernelversion 5.3.7

DaVinci 644x based system

configname: CONFIG_ARCH_DAVINCI644x

Linux Kernel Configuration
└─>TI DaVinci Implementations
└─>DaVinci 644x based system
In linux kernel since version 2.6.22 (release Date: 2007-07-08)  

is selected by
CONFIG_MACH_DAVINCI_EVM